It is well established that computer keyboard operators may be subject to repetitive strain injury (RSI) which is believed to arise from inadequate support of the wrists and forearms of the operator. Various proposals have been advanced for alleviating the problem, ranging from simple expedients such as increasing the depth of the front apron of the keyboard, to more complex expedients of an add on nature.
In the ensuing brief description and throughout the specification, reference is made to a single support unit for one wrist only, for the sake of clarity. However, it will be understood that in most instances, for keyboarding operations two such units will be employed, and that while these may be identical and physically separate, this is not necessarily the case, as they may be integrated to a greater or lesser degree into a single unit.
In other instances, a single unit may be all that is required, as might be the case where the unit is intended to provide wrist support for operating a computer mouse for an extended period of time.
U.S. Pat. No. 5,072,905 (Hyatt) describes a device with a support strut that is rotatable in a horizontal plane about a vertical axis (z axis), but which is intended to be secured in a predetermined position, and a cushion supported in a fixed manner from the support strut.
U.S. Pat. No. 5,201,485 (Moss et al) describes a device wherein a support strut is movable so as to be:
(a) freely pivotable about the Z axis; PA1 (b) freely slidable along its length. PA1 (a) rotary movement about a yaw axis; PA1 (b) pitching movement about a pitch axis; PA1 (c) rolling movement about a roll axis.
A cushion is supported from the distal end of the support strut so as to be freely pivotable about a yaw axis parallel to the Z axis, and in addition to pitch in a fore and aft direction relative to the longitudinal axis of the cushion. The pitch motion is controlled in part by biasing springs which bias the cushion to a neutral pitch position when an out-of-balance force is removed from the cushion.
U.S. Pat. No. 5,161,760 (Terbach) describes a device that is similar to that of Moss et al, but in addition, the support strut is freely slidable along a horizontal axis parallel to the keyboard axis.
It is also known to use as a support an articulated strut which pivots freely about its proximal end and at a point intermediate the proximal and the distal end. In accordance with one such proposal, the proximal portion of an articulated strut is formed as a hinged parallelogram which permits the height of a support cushion supported on the articulated strut to be adjusted.